fix(flutter): add SDKError rethrow to transcribeWithResult

Addresses CodeRabbit nitpick on #456 (comment 3958436625). Mirrors the
`on SDKError { rethrow; }` pattern that `transcribe()`, `generate()`,
`generateStream()`, and `synthesize()` already use, so validation and
structured SDK errors don't get logged as generic `transcription_failed`
telemetry events.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: sanchitmonga22

sdk/runanywhere-flutter/packages/runanywhere/lib/public/runanywhere.dart

@@ -748,6 +748,10 @@ class RunAnywhere {
         durationMs: audioDurationMs,
         language: result.language,
       );
+    } on SDKError {
+      // Re-throw validation / SDK errors so callers see the structured error
+      // instead of it being logged as a generic transcription failure.
+      rethrow;
     } catch (e) {
       // Track transcription failure
       TelemetryService.shared.trackError(